Persistent configuration; Load and use proxy configuration.

[Jancis]

• Provides config get and config set commands
• Provides persistent configuration storage.
  • Linux location: /home/<user>/.config/silta/
  • Windows location: C:\Users\<user>\AppData\Local\silta\
  • Mac OS location: /Users/<user>/Library/Application Support/silta/
• Sets http proxy environment variables in application scope whenever a non-empty proxy configuration item is found

Testing:

1. Set context to a cluster that requires connection
2. Load release information via silta ci release info --release-name <release-name> --namespace <namespace>. Should fail.
3. Set proxy configuration silta config set proxy localhost:1234 (do not create tunnel yet).
4. Load release information again. Should fail again but with a message "proxyconnect tcp: dial tcp [::1]:1234: connect: connection refused"
5. Run ssh tunnel ssh -D 1234 -C -N <tunnel_host>
6. Load release information, should succeed.

[Rade333]

This is great, thank you!